1. Field of the Invention
This invention relates to a process for applying an identification to an object made of a porous material and more specifically to placing an identification on building materials such as paving bricks that utilizes a hardenable filler in an engraved identification thereon.
2. Description of the Prior Art
In the prior art the usual practice for applying personalized identification to porous hardened building materials such as bricks has been to impress the desired identification into the soft clay before the brick is hardened. This is an acceptable practice when the same identification is repeated on a large volume of bricks. However, there is an increasing need to apply customized unique identification to building materials. For example, bricks are widely used for paving. Many customers desire customized identification on their paving bricks which may include letters, numbers or designs. The application of surnames, company names and addresses is most frequently desired and it is not unusual for a customer to request customized identification on several hundred or more bricks. In those situations wherein a custom identification was required for each brick or on a small number of bricks, it has been the practice to carve the identification on each brick or other object in some manner after the brick has been hardened. The reason for carving is that the cost of making and changing the brick molds with individualized identification where only one or a small number of bricks are to be produced is prohibitively expensive. However, stone carving is also expensive and not economically feasible for manufacturing runs of several hundred bricks.
Another problem that arises is that when an identification is embossed or carved into the brick, the recessed area is of the same general color as that of the brick and thus offers little or no color contrast. Lack of color contrast results in the identification not being readily discernible and appreciated esthetically even at short viewing distances. To overcome the lack of discernibility, it is a known practice to place some type of settable or hardenable filler, preferably of a contrasting color, in the embossed or carved identification. Applying the filler only into the engraved identification and not the adjacent surface is very difficult, slow and costly. Thus the practice has developed of wiping the filler over the surface of the brick to impress it into the embossed identification. The drawback to the practice of wiping is that the filler is also impressed into the pores of the brick. The filler impressed into the pores makes the brick unattractive and must be removed. Removal of the filler from the surface around the identification is expensive and in some instances impossible. For example, one of the most preferred fillers is epoxy resin because it flows easily into the identification, is extremely durable under all service conditions, and has tenacious gripping ability. Ironically, these desirable qualities make epoxy fillers extremely difficult to apply to porous materials such as paving bricks.
The use of stencils or masks to keep the epoxy off of porous surfaces adjacent the identification is common. Even when masking stencils are used around the identification the epoxy tends to leak under the stencil or mask and flow or run onto the surrounding surface. This leaking is compounded when pressure is applied, for example, by a putty knife, frequently used to assure uniform filling of the identification. Moreover, if the stencil is left on the brick until after the epoxy hardens, removal of the stencil becomes more difficult, and if the stencil is removed before the epoxy hardens there is risk that removal may cause excess epoxy in the identification to inadvertently flow onto surfaces adjacent the identification. There is no practical way known to dissolve hardened epoxy and remove it from the pores of the brick, and surface grinding is expensive and may be unacceptable because it changes the texture and appearance of the surface of the brick.
Thus heretofore the prior art has not disclosed a low cost efficient process to enable individualized embossed or engraved identification to be placed on objects made of porous material and then filled with a filler such as epoxy resin to highlight such identification in a neat and clean manner which will result in a finished product having no unwanted filler in the pores of the surface adjacent the identification.